In a railway car, the primary suspension system generally refers to the suspension between the journal bearing assembly and the truck frame. The journal bearing assembly carries wheel axle units and acceleration forces generated by the wheels are transmitted through the primary suspension system to the side frames. The secondary suspension system refers to the system between the truck body and the car body. The present invention is directed to a novel truck having improved primary and suspension systems.
Many past primary suspension systems have involved elastomeric rings surrounding the journal bearings. Such rings have included cut-away portions to provide softer spring rates and the cut-away portions were designed to provide desired vertical longitudinal and lateral spring rates. Some of the primary suspension systems used heretofore are described in a U.S. Pat. No. 4,044,689, to Eggert issued Aug. 30, 1977 and in a copending application, assigned to the same assignee as the present invention, of Eggert entitled "Suspension System for a Railway Car", now U.S. Pat. No. 4,438,703, filed Feb. 12, 1982. Also, a pending application of Herring, Ser. No. 522,758, filed Aug. 12, 1983 relates to a primary suspension system not involving elastomeric rings.
When primary suspensions are made extremely soft, the excursion of the truck frame is quite excessive. Therefore, there are other things that must be done. It is important that means be provided to maintain the correct alignment and relationship of the third rail collector devices, the waveguides and trip switches and other devices on the truck that are used for signalling and control and power pick-up. All of these devices must run in a fixed relationship to the distance between the wheels and the rail.
In designing primary suspension systems, it is often desirable to be able to independently adjust the spring rates in the longitudinal, lateral and vertical directions. Different design requirements and car weights require different ratios between the spring rates involved. Independent adjustments of all three spring rates are normally not achievable with existing primary systems.
When very soft primary systems are employed, consideration must be given to the secondary suspension system. Generally, springs are disposed between the truck and the car body. When there is excessive movement between the car body and truck, the springs tend to distort. It is desirable that the vertical springs be maintained in vertical positions during relative movement between the car body and truck.
In conventional systems, the load from a car body is transmitted through a center king pin to a bolster fixed to the side frame. This arrangement generally results in added weight to the truck.